High-tension transformer



Jan; 22, 1929. 1,699,763

H; B. SMITH HIGH TENSION TRANSFORMER Filed Oct- 1925 5 Sheets-Sheet 1ETNESSES: INVENTOR 4 B/Zaro/d 5. Sm/M.

MW 3W A w ATT'ORNEY Jan. 22, 1929 1,699,763

H. B. SMITH HIGH TENSION TRANSFORMER Filed Oct. 1, 1925 5 Sheets-Sheet 2F/ 5 D i C I I I l I I I 6 I U) I B I A I I I I I I I I I I I I I l A FO/sfance. E

WITNESSES:

INVENTOR HGl/TO/d B. Sm/fh, BY

Jan. 22, 1929,

1,699,763 H. B. SMITH HIGH TENSION TRANSFORMER Filed Oct- 1925 5Sheets-Sheet 5 WITNESSES INVENTOR l4 I Hg rold 5. 507/772. Wt-W 4 WATTORNEY Jan. 22, 1929. Y 1,699,763

H. B. SMITH HIGH TENSION TRANSFORMER Filed Oct. 1925 5 Sheets-Sheet 4'F006 /5 f L I WITN ESSZ: /C;NEN\OR .a/o m/ @777. BY

; W ATTORNEY H. B. SMITH HIGH TENSION TRANSFORMER Jan. 22, 1929-1,699,763

Filed 001?- L925 5 Sheets-Sheet WITNESSE INVENTOR' @571. 5 m y Hare/d53/77/771.

AT'TORNEY Patented Jan. 22, 1929.

UNITED STATES PATENT OFFICE.

HAROLD B. SMITH, OF WORCESTER, MIASSACHUSE'ITS, ASSIGNOR TO WESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

HIGH-TENSION TRANSFORMER.

Application filed October 1, 1925. Serial No. 59,820.

My invention relates to electrical translating devices and particularlyto high ten It is also an object of my invention to pro-- vide anelectrical translating device for high tension service in which theseveral structural elements are all provlded with curved surfaces, therespective radii of curvature ofwhich are of such Va lues that theconcentration of corona forming or incipient ionization potentials areavoided.

It is a further object of my invention to provide an electricaltransformer for high tension service in which the electromagnetic andelectrostatic fields between the several windings of the transformer,the windings and the supporting structures, and the windings and groundare so distributed that the development of corona or incipientionizationforming potentials on any surface are prevented.

It is a well-known fact that the insulating values of oil intransformers, circuit breakers and the like deteriorates rapidly byreason of the presence of carbon, sludge, moisture and the like, Certainof the aforenamed deleterious agents are the products resulting i fromdecomposition of a certain amount of the insulating oil itself. So faras I am now advised, no previous effort has ever been made to improveoperating conditions for such insulating oils at potentials that arecapable of corona formation.

I have found that at certain voltages a I propose to prevent thedevelopment of corona or incipient ionization forming potentialswithinthe transformer by removing all sharp edges from the several structuralelements and by interposing such suitable shields in the electrostaticand electromagnetic fields that the potential gradient between theseveral shields shall not exceed such corona forming or incipientionizing values.

In electrical translating devices as heretofore constructed, it has beenfound that where distance alone was relied upon to provide properinsulation between electrically charged bodies, even though theintervening spaces were filled with insulating material such as oil,impregnated insulating material, and the like, that, at the highervoltages, such distances had to be increased in aratio much greater thanthat directly proportional to the 'voltage increases.

The result of this need for increased spacing between the electricallycharged bodies is such that very high potential transformers relyingupon insulation filled space alone for insulation are so cumbersome asto be virtually impossible of manufacture. I have found that by suitablyarranging and controlling the potential gradients between the severalelements of a transformer at differences of potential so that thepotential gradient at any surface is kept below the corona or incipientionization potentials, that I am enabled to very greatly reduce thespace required between the several elements at differences of potentialover that hitherto necessary for the same voltages.

In the accompanying drawings, I

Fig. 1 is an elevational view of a transformer embodying my invention.

Fig. 2 is a View, partially in elevation and partially in section, ofthe transformer shown in Fig. 1. i

Fig. 3 is a curve showing the relation be-. tween the spacing ofconducting members and applied voltages.

Fig. 4 is a fragmentary plan view of the transformer.

Fig. 5 is a sectional view of one side of the transformer windings.

Fig. 6 is a view, partially in elevation and partially in section, of aslight modification ment of the metallic shields about the distributingbushings, and

Fig. 7 is a' similar view of a second modified form of my invention.

Fig. 8 is a diagrammatic plan view of another modified form of myinvention.

Referring particularly to Figs. 1, 2 and 5, my invention comprises, ingeneral, a transformer 1 disposed in acasing 2 and comprising a hightension winding 3 consisting of a plurality of coils 3a of pancake formdisposed concentrically about a core member 4 and a low tension winding5. The several coils 3a are provided at their outer edges with metallicpotential andflux distributing members 6 of toroidal form, to certain ofwhich are attached nested metallic shields 7 of annular form, fordistributingthe potential and flux fields generated within thetransformer.

The upper coil 8 of the high-tension winding 3 differs from the pancakecoils 3a in that it is formed by a plurality of turns of pipe formedinto a spiral that also serves as a single protector by permittingdischarge of excess local potentials between turns through theinsulating medium. The upper contour of the entire coil 8 is curved sothat no corona forming potentials may develop thereon.

The details of the structure associated with the distributing terminal9, illustrated in Fig.

1, are shown in Fig. 6. The terminal'9 which is electrically connectedto the outer terminal of the coil 8 extends upwardly through the ,casing2. The several shields 7 have extensions 11 that are disposed in nestedrelation and also project upwardly and out of the casing 2 in parallelrelation to the distributing terminal 9. The extensions 11 aresever-ally connected externally of the casing 2 to horizontallyextending portions 12 that terminate in toroidal potential and fluxdistributing members 13. The toroidal members 13 are accordinglydisposed concentrically about the distributing terminal 9 in such mannerthat the potential gradient therefrom to the casing 2 is maintained ator below corona or incipient ionizing potentials.

The diameter of the several toroids 13 decreases successively outwardlyfrom the terminal 9. The diametersof'these successive toroidal memb e rsmust be determined from a consideration of the limiting potential gradient at their surfaces toflremain below the point-of corona formation.This must be considered with reference to both the potentials betweenadjacent toroids and to the total potential of any one of them to earth.I have made use of toroidal members 13 whose diameters vary from threeto nine inches for a a transformer originally designed for generating1,000,000 volts.

Referring particularly toFig. 5 the terminal of the lowermost coil 3a isconnected by a suitable conductor 14 to the casing 2 of the transformer,thereby grounding that terminal of the high-tension winding 3. Theseveral pancake coils 3a are connected directly to the upper coil 8 andthe latter is connected to the distributing terminal 9, thereby placingthe several COIlS 3a and the coil 8 in series connection between theterminals 9 and 14. The several coils 3a are separated, from each otherbysuitable insulating bodies 15 of fuller board or the like. The innerand outer edges of certain or all of the coils 3 are provided with atoroidal distributor 6 in order' to prevent the. accumulation of coronaforming potentials at the edges of the several coils 3a. The distributor6 may, or may not, constitute the outer turn of the winding 3 asdesired. Also, the distributor 6 may be omitted if desired.

Certain of the distributors are attached to distributing shields 7 sodisposed as to keep the potential gradients therebetween below coronaforming potentials. The several shields 7 are of annular form, and,except for a small gap, extend entirely around the core member, onewithin the other, thereby providin the effect of toroids. The shieldsare provi ed with suitable openings 16 for permitting a circulation ofthe insulating fluid 17 therebetween. The upper surfaces of the annularshields 7 are provided with corru-.

gations 18 constituting air traps andare provided with perforations 16.

In assembling the metallic shields 7 of the transformer shown in Figs.1, 2 and 5, they are placed in position in sections. The annularportions of the several shields, together with their inwardly projectingbottom portions, are placed in position prior to the securing of theupper end or cover portions thereto.

The annular portion of the outermost shield is first placed in positionand connected at itsbottom portion to the outer turn of thecorresponding coil. The annular portion bodies. At the voltage G adistance F will safely insulate these bodies and the curve between thepoints A and B is substantially a straight line. However, at a voltage Dthe corresponding point C required at insulating distance E that is notdirectly proportional to the voltage D and the distance F. This curveclearly illustrates that there is for insulation filled space, a limitbeyond .which it is not economical to rely upon distance alone ininsulating bodies between which there is a difference in potential. Bythe use of the combination of distributing toroids and shields, I amenabled to place bodies having a difference of potential materiallyclosed together, than has heretofore been possible, by reason of theelimination of corona or incipient ionizing potentials at any pointwithin the transformer.

In Fig. '6, the arrangement of the shields differs from that of thetransformer shown in Figs. 1, 2 and 4 in that the annular portions 21and the bottom portions 22 are in separate parts, each part beinprovided with a toroidal portion 23 that abut each other when the partsare assembled. In this. arrangement, the bottom portions 22 of theshields are placed in position successively, beginning with thelowermost one. The annular portions 21 are then placed in position inany desired order.

The extensions 11 of the metallic shields are assembled by placing theinnermost extension in position adjacent to the corresponding annularportion of the shield and t en placing the remaining extensions inposition progressively outwardly. The members 12 are then placed inposition with respect to the corresponding extensions 11 by placing thelower-most member, or member of greatest diameter, in position and.then

proceeding progressively upwardly to assemble the remain'ng members.

The structure hown in Fig. 6 does not differ in principle from thatshown in Figs. 1, 2 and 5, but this arrangement aifords'considerableconvenience in assembling the parts, as the necessity for electricallywelding or otherwise connecting the adjacent edges of the parts of themembers is avoided. The provision of the toroidal members 23 on theadjacent edges of the parts. of the shields avoids the concentration ofpotential or flux at these points and thereby prevents the formation ofcorona or incipient ionization.

Referring particularly to Fig. 7 I have shown a modification of theinvention in which the terminal 9 passes through a materially largeropening 31 in the transformer casing 2 and the shields 32 terminatedirectly in toroids 33 that are disposed within the casing 2 and thatare distributed in progressivelydecreasing radii outwardly from theterminal in a manner similar to that of the modification shown in Fig.6. In other particulars, these two forms of my invention are similar.

Referring to Fig. 8, I have shown a form of my invention in which arectangular core member 31 has a low tension winding 32 disposed abouteach of its sides. The several low tension windings 32 are connectedbeionizing potentials.

tween a source of electromotive force 33 and a ground connection 34.

Surrounding each of the low tension windings 32 are one or more metallicshields 35 that separate the low tension windings from the coils 36 of ahigh tension winding. The several coils 36 of the high tension windingare each disposed in the form of a cylinder about one section of thecore 31 and are separated from each otherby one or more metallic shields35. The length of the several shields 35 and coils 36 decreasesoutwardly from the core 31 by reason of physical contact with thesimilar cylinders wound upon adjacent core sections, as is clearly shownin the draw ing. At the points of contact between the several cylinders,toroidal distributors 37 are provided which engage each other andprevent accumulation of corona or incipient The several coils andshields are connected in series relation between a ground conductor 38and a distributor 39.

This form of my invention diilers from the other forms only byitsadaptation to a transformer having a rectangular core.

By means of the present invention, I have provided an electricaltransformer that is characterized by the provision of suitabledistributing toroids and shields that prevent the accumulation of coronaforming or incipient ionizing potentials at any point within thetransformer. By making the several radii of curvatureproportional to thepotential to which the members are-subjected, I am able to control thepotential gradient at or near their surfaces in the desired manner; Byeliminating the occurrence of corona forming or incipient ionizingpotential gradients within the insulating medium of the transformer, Iam able to prevent the deterioration of the insulating medium and at the.same time dispose my bodies having a difference in potential atdistances from each other that are materially less than the limitsheretofore existing in such devices. It is to be understood that suchchanges may be made in the structure and arrangement of the severalparts as fall within the scope of the several claims.

I claim as my invention:

1. In a transformer, a'core member, a low voltage winding associatedtherewith, a high voltage winding and a plurality of'nested toroidalmembers associated with the high voltage winding and dividing it intosections.

2. In a transformer, a plurality of coils, insulating material disposedbetween adjacent coils, separate potential control and flux distributingmeans of annular form surrounding certain coils, and otential con troland flux distributing shie ds electrically associated with certain ofsaid distributing means.

3. In'a transformer, a plurality of coils,

{and flux distributing s ciated with certain of said distri uting means.a

'- 4. In a transformer, a plurality. of coils,

insulating material disposed between adja- {insulating material.disposed between adjacent coils, separate potential control and fluxdistributing means of annular form sur*- rounding certain coils andpotential control hields electricall assocent coils, a separatepotential control and flux distributing means surrounding each 0011 andpotential control and flux distributing shields electrically associatedwith certain of said distributing means. A

5. In a high potential winding, a plurality of coilsdisposed in verticalalinement, the

end coil having a contour, the radius of curvature of which is such thatthe potential graclient at or near its surface is less than will formcorona or incipient ionization.

6. In a high potential winding, a plurality of coils disposed invertical alinement, the end coil having a contour, the radius ofcurvat'ure of which is such that the potential gradient at or, near itssurface is less than will form corona or incipient ionization, said endcoil comprising a helix of tubular conducting material.

7. In :a; high potential winding, spluralityof coils disposed invertical alinement, a terminal coil having a contour, whose radius ofcurvature is such that the potential "gradient at or near its surface islessthan a corona or incipient ionizing potential, the

last-named 'coil comprising a continuous helix of conducting material.

8. In an electric translating device, a plu 'rality of coils, aninsulating fluid surrounding the coils, and nested potential control andelectric fluxdistributors of toroidal form attached to certain of thecoils and immersed in the insulating fluidfor the preventionof corona orincipient ionizing potentials in the insulating fluid. I

9. In an electrical translating device, a plurality of space coils thatare subjected to pro gressively increasing potentials. in accordancewith their spaced disposition, an insulating fluid surrounding thecoils, and potential control and electric flux distributing meanscomprising a plurality of metallic shields of split annular form anddistributors of toroidal form secured to certain of the coils andimmersed in the insulating fluid, the radii of curvature of the severaltoroids injcreasing in accordance with the progressive increase inpotential of the several which they are connected.

coils to' 10. an electrical translating device, -a

plurality of coils, an insulating fluid, surrounding the coils, andnested potential distributors of toroidal form attached to certain ofthe coils and immersed in the insulating fluid for the prevention ofcorona or iincipient ionizing potentials in the insulating uid.

11.'In an electrical translating device, a plurality of coils, aninsulating fluid surrounding the coils, and nested electric fluxdistributors of toroidal form attached to certain of the coils andimmersed in the 1nsuroidal form surrounding the terminal member and inelectrical connection with the firstnamed distributors.

13. In an electrical translating device, a, plurality of coils, aninsulating fluid sur rounding the coils, and nested potentialdistributors of toroidal form attached to certain of the coils andimmersed in the insulating fluid for the prevention of corona orincipient ionizing potentials in the insulating fluid, a terminal memberfor the device and nested potential distributors of toroidal formsurrounding the terminal member and in electrical connection with thefirst-named distributors.

14. In an electrical translating device, a plurality ofjcoils, aninsulating fluid surrounding the coils, and nested electric. fluxdistributors of toroidal form attached to certain of the coils andimmersed in the insulating fiuidfor the prevention of corona orincipient ionizing potentials in the insulating fluid, a terminal memberfor the device an nested electric flux distributors of toroidal formsurrounding the terminal member and in electrical connection with thefirst-named distributors. v

In testimony whereof, I have hereunto subscribed my name this sixteenthday of September, 1925.

HAROLD B. SMITH.

